Method of making dinitro cresol



for exceptional purity.

Paj tntedAug, 3,1943

METHOD on 2,325,153] e e MAKING nmrrno oansor.

ime n non, Plainfield, and AlfredfG. mu, North Branch, N. J.,, as signors;,to'American New Y r-MN Y., a cor- Cyanamid Company,

" notation of Maine No l lirawing, Application 2, 194 1,

seriamasrassr 3 cleans.

the preparationof the dinitro cresolsn: 1

A known method of nitrating cresols involves nitration at a very low temperature requiring extensive refrigeration,'the reaction being carried out for a'period of at least ten hours. This method is unsatisfactory due to the cost of maintaining the reaction mixture at the low temperature specified, while the, lengthyreaction 1 period results in an extremely long time cycle.-

The principalobject ofthe present invention I is to improve the above method byf'inducing a I smooth, easily controllable reaction, whichelimi hates costly refrigeration while atthe same time 1 materially cutting down on the nitration period and, consequently, the time cycle; e

1:": e The present invention is based on the observation that by adding the lsulfonatio'n mixture to about]30 minutes followed by heating of from to 2 hours to approximately 80 to 100 C. prof J vided that theresultantmixture iscooled to 80, i 1 to 85, C. The above procedure has been found to result in aconsiderable saving of time in the nitrationperiod while producing adinitro cresol 1 Example I 39,51grams of crew];

, 93% sulfuric, acidwasadded during five minutes to ZI'grams of pureortho;

The temperature rose j from" 25: C.

about 65 C. Thernixture was heated at from: x '15 to 80 C; for: minutes. 1 A 23% solution of e (01. z st-r22) a The present invention relatesto methods to of an exothermic reaction were noted [at GO *The'seeondprecipitatemelted at 80.

, as 100C. was reached, the mixture was allowed to cool to 80 to 85 C. and'then run into 920 cc; The precipitated material was As soon 01 cold water. filtered, washed and dried. The dinitro' ortho' ,cres'ol thus prepared had alight yellow color and a melting point of 86 to 87 C.

I Example II starting material. produced had a melting point of from 79 to8l C. While the invention has been described with particular reference to specific embodiments, it i istobe'understood that itis not to be limited thereto but is to be construed broadly and re-;

stricted solely by the scope of the appended claims; H k i .We claim;

1.; A method of preparing a compound selected from the group consisting otdinitro-o-cresol and:

dinitro-p-cresol, which includes the following steps, forming a cresol sulfonation mixture from 1 concentrated sulfuric acid and a compound sei lected from the group consisting of ortho'cresol q and para 'cresol, adding the sulfonation mixture ,1 to dilute nitric acid at room temperature with I agitation while allowing the temperature torise to substantially 40 C.,' thereafter heating the' mixturetoimm 80 C. to 100 C., and subserquently isolating the dinitro cresol. 1

2. :A method of preparing dinitro-o-cresol which includes forming a cresol sulfonation mix ture from concentrated sulfuric acid and ortho i cresol, addingthe sulfonation mixture to dilute nitric'a'cid at room temperature .with agitation nitric acid was prepared by adding '68'grams of 69% acid to ,136 grams of water; It has been found more advantageous to dilute the nitric, acid solution to the proper concentration-rather than to dilute the sulfonation mixture with water, i Q'I'his dilute'acid was'then cooled tocfro m th C. and the sulfonation mixture added-at that v temperature with stirring for a period of 30min utes. At this point; a light ,precipitate was,

i formed] The solution was heated, to the boil in s about? hoursat a constant rate. Thefirst prej-j; cipitate melted ordis solved at C; andanew one began to appear at about C. Evidences I while allowing the, temperature to" rise to substan tially 40C., thereafter heating the mixture to from C. to C., and subsequently isomung, the dinitro-oecresol;

3; A method of ipreparing dinitro-p cresol 1 V which includes forming, a 'cresol sulfonation mix lwhil'e allowing the temperature to rise to sub ls'tantially 40 C., thereaiterheatingthe mixture 5 ttiigfrorn--,80 vC. to l00 0., andsubsequently isof latingthei dinitro-pcresol: 1 1

M UR CE Li L715. j u

v The sameprocedure as set forth aboveqwas efollowed using, however, a 'para cresol as the l1 The dinitro para cresol thus 

